Natural History

Although great hammerhead sharks (Sphyrna mokarran) appear powerful and robust, recent research has shown that they are in fact one of the most fragile shark species, being particularly vulnerable to the stress of capture. Even those that are released after being hooked have a nearly 50% chance of succumbing after their ordeal.1 To better protect these sharks, a greater understanding of their movements is needed. The results of a new study conducted by scientists at the Bimini Biological Field Station in Bimini, Bahamas have provided a major step forward by showing the migration patterns and regional connectivity of great hammerheads between the Bahamas and the United States.

Although the image of the shark as a solitary predator may pervade the public consciousness, new research is showing that at least one shark species exhibits complex social behaviors normally associated with higher order mammals. A team of University of Delaware scientists led by PhD candidate Danielle Haulsee has been using technology to study sand tiger sharks (Carcharias taurus) along the east coast of the United States. Sand tigers are ferocious-looking, but quite docile, sharks that inhabit warm, coastal regions throughout the world (with the exception of the eastern Pacific). As a result of their study, Haulsee and her colleagues are showing that sand tigers may have a much more enriching social life than we ever could have imagined.

There are few marine creatures as fascinating to watch as cephalopods. From their tentacles that each seem to move autonomously, to their unbelievable ability to change colour and texture, to their alien feeding habits, these molluscans never cease to amaze us.

Although they may look absolutely nothing like clams, cephalopods are considered mollusks and are more closely related to bivalves than any other group of sea creatures. Octopuses, squid, cuttlefish, and nautiluses all belong to the class Cephalopoda, which means “head foot.” Mollusks in general are not known for their intelligence and most don’t even have a proper head, let alone an impressive brain, but cephalopods differ drastically in this regard.

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